Others have covered many good qualitative points. The math of how much you can afford is very subjective, as it is tied to your personal spending habits and also how much you are comfortable spending vs. saving. The math involved will also depend on your tax bracket and also local/state tax rates (income as well as property taxes), which can vary substantially. That said, math like this is pretty reasonable:

-You want your monthly total payment to be covered, say, 50X by your annual gross income.

-This puts you at monthly total payment of $1,400 [to cover P&I, insurance, and property taxes]

-Assuming property taxes of 1% of home value and homeowners insurance of 0.3%, so 1.3% total.

-Assume a 30-yr mortgage at 3.9% with a 20% downpayment.

Based on these assumptions, you could afford a $289,000 house, which would give you a $231,000 mortgage. The mortgage payments would be $1,090/mo and insurance/taxes would be about $310/mo, for a total of $1400. This does ignore maintenance on the house; if you build in $100/mo of maintenance, you'd need to reduce your budget by approx $15-20K [down to $270K or so] in order for the $1400/mo to still be accurate.

Then, whenever doing a calculation like this, you can stand back and ask if it passes a sanity check. A person making $70K brings home something like $4200/mo, again depending on area you are living. The $1400/mo assumption means you spend 1/3 of post-tax income on housing, which is reasonable, although maybe not by MMM standards. That said, when you incorporate tax advantages from interest deduction, it becomes less than 1/3 so you would be well covered.

Anyway, basically this is the framework you can fill in, using your own assumptions.